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    <title>Document</title>
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<body>

    <h1 id="a"></h1>
    
    <script>
        var oH1 = document.getElementById('a') ;

        var date = new Date() ;
        var h = date.getHours() ;
        var m = date.getMinutes() ;
        var s = date.getSeconds() ;
        oH1.innerHTML = h + ":" + m + ":" + s ;

        

        setInterval(function() {
            var date = new Date() ;
            var h = date.getHours() ;
            var m = date.getMinutes() ;
            var s = date.getSeconds() ;
            // document.write(h + ":" + m + ":" + s) ;
            oH1.innerHTML = h + ":" + m + ":" + s ;
        } , 1000)

    </script>
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